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Need help w/ arranging resultant vector with 3 other vectors. D:

  1. Oct 28, 2007 #1
    1. The problem statement, all variables and given/known data
    Find the vector combination R = A + 2B - C. Grid lines are separated by 1 cm. When you submit your answer the third vector that you drew may disappear, but if you are correct you will have a green check mark near the grid. (Mac OS X use Netscape, Windows use IE.) A scratch vector is provided for your use if needed.


    2. Relevant equations

    3. The attempt at a solution
    A x=-3 y=2
    B x=-1 y=-1
    C x=-2 y=1
    R x=-3 y=-1

    I tried using the tip to tail method for joining the vectors, but it didn't work since the vectors don't fit. Maybe I have to use the parallelogram method here? I really have no idea. :( Any help is appriciated.
  2. jcsd
  3. Oct 28, 2007 #2
    You already know the equation for the resultant, and the components of each vector. If I have an equation for the resultant, say R = 2A - B, where A and B are vectors, and I know that A = < 1, 2 >, and B = < 3, 4 >, I can find the resultant by plugging the vector components into the resultant equation:

    R = 2< 1, 2 > - < 3, 4 > = < 2, 4 > - <3, 4 >

    Add the components:

    < 2, 4 > - <3, 4 > = < -1, 0 >

    Now we know that the resultant should be the vector < -1, 0 >, where -1 is the x component, and 0 is the y component.
  4. Oct 28, 2007 #3
    Thanks, but I already have found the components of the vectors. I was asking how to do the graphical part, like where you arrange the vectors and the resultant. >_>
  5. Oct 28, 2007 #4
    Look at your equation, there's a minus signal in front of vector C. That equals to the sum of vector C, just in a opposite direction.
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